Back cavity of an iron club



FIG. 1 is a heel-side perspective view of my new back cavity of an iron club;

FIG. 2 is a toe-side perspective view thereof; and,

FIG. 3 is a back view thereof.

The broken line showing is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a back cavity of an iron club, as shown and described. 